The present invention relates to a valve device that opens and closes a passage of a fluid.
A typical valve device for opening and closing a passage of fluid uses an electromagnet. Japanese Laid-Open Patent Publication No. 2000-81162 discloses such a valve device. This valve device has a valve body (valve member) for opening and closing a passage of a valve main body that moves fluid. The valve body is made of magnetic material. The valve body is coupled to a film that is movably supported by the valve main body. An excitation coil is wound about the outer circumference of the fluid passage of the valve main body. When the coil is excited, an electromagnet is provided. When the excitation coil is excited, the valve body, which a magnetic material, is attracted or repelled thereby opening or closing the passage.
The valve body and part of the fluid passage must be made of magnetic material. Therefore, the electromagnet must be arranged close to the valve body so that magnetic force of the electromagnet is transmitted to the valve body. Therefore, the material for the valve member must be selected from a limited number of materials, which restricts selection of the valve member and limits the flexibility of the design. Also, the excitation coil must be wound about the outer circumference of the fluid passage of the valve main body. This complications the structure of the device and increases the size of the device.